Rotatable valve assembly with plug seal

ABSTRACT

A rotatable valve assembly ( 20 ) is disclosed. In one embodiment, the rotatable valve assembly ( 20 ) includes a valve body ( 22 ) and a valve plug ( 24 ). The valve plug ( 24 ) includes a seal configured to form a fluid-tight barrier with an interior surface of the valve body. The rotatable valve assembly may include additional seals, including a seal ( 96 ) provided in the valve body ( 22 ). The rotatable valve assembly ( 20 ) further may be used with a release mechanism ( 40 ) to control the pressure at which the valve plug ( 24 ) rotates into an open position.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Application No.61/959,845, filed Sep. 4, 2013, the entire contents of which are herebyincorporated by reference.

FIELD

The present disclosure relates to a system for relieving pressure from apressurized system. More particularly, the disclosure relates to arotatable valve assembly that may be used as a pressure relief device.

BACKGROUND

There are many types of systems that process or use a pressurized fluid,To ensure the safety of these types of systems, each such systemtypically includes a safety device designed to prevent theover-pressurization of the system. In an emergency situation, where thefluid in the system reaches an unsafe level, the high pressure of thefluid acts on the safety device to create an opening to release fluidfrom the system. Venting fluid to the environment or a safety reservoirthrough the opening reduces the pressure in the system and preventsanother portion of the system from failing due to the high pressure ofthe fluid. Examples of known safety devices are disclosed, for example,in U.S. Pat. Nos. 3,472,284, 3,039,482, 2,304,491, 3,603,333, 4,724,857,4,787,409, 4,930,536, 4,977,918, 5,012,834, 5,067,511, 5,116,089,5,146,942, 5,209,253, 5,226,442, 5,273,065, 5,297,575, 5,311,898,5,318,060, 5,348,039, 5,373,864, and 5,433,239.

One type of safety device for a pressurized system is a pressure reliefvalve, which may be a reclosing valve or a non-reclosing valve.Typically, a spring, a pin, or a combination of a spring and pin, isused to hold a moving plug in sealing engagement with the body orhousing of the device while connected to the pressurized system. Whenthe pressure of the fluid reaches the predetermined safety level in suchsystems, the force exerted on the plug by the pressurized fluidovercomes the bias of the spring or exceeds the resistance of the pinthat holds the plug in place. When either of these events occurs, thepressurized fluid moves the plug to expose an opening through whichfluid may escape to relieve the pressure in the system. Reclosing valveswill automatically reset once the pressurized fluid at the inlet of thedevice has reduced sufficiently for the spring or other mechanism toreseat the plug. Non-reclosing valves require that the device bemanually reset so that the valve plug is re-engaged with the seal and,if necessary, the pin or other expendable component replaced.

One type of pressure relief valve is a rotatable valve assembly. Knownrotatable valve assemblies are disclosed in commonly owned U.S. Pat.Nos. 5,607,140, 5,947,445, 6,098,495, 6,367,498, 6,488,044, and6,491,055, the entire contents of each of which are expresslyincorporated herein by reference. A rotatable valve includes a plug thatis mounted on a rotatable shaft and may be rotated between a closedposition where the plug blocks the flow of fluid and an open positionwhere the plug allows fluid to flow through the valve. The rotation ofthe plug to the open position may be initiated manually or by anotherexternal force. Alternatively, the plug may be mounted on the shaft sothat the rotational axis of the plug is offset relative to the center ofthe plug, so that the pressurized fluid exerts a torque on the shaft andurges the plug to rotate. A device may be coupled to the shaft toprevent the shaft from rotating until the torque on the shaft reaches acertain level, indicating that the pressure of the fluid has reached anover-pressure situation. At that point, the shaft is released and theplug rotates to open the valve and vent the system.

A valve disposed in a pressurized system will often include a sealbetween the body and the plug to limit or prevent fluid from leakingthrough the valve. As illustrated, for example, in U.S. Pat. No.6,367,498, a known seal is disposed in a valve body and is configured toengage with the outer perimeter of the valve plug to prevent pressurizedfluid from flowing between the plug and the body while the valve isclosed. Because a known seal is disposed in a valve body, it is heldstationary while the valve plug rotates. As such, there is limitedcontrol over the sealing mechanism, including the interface betweenmoving and non-moving parts of the valve assembly. In addition, thevalve body is subject to deformation in the event of irregular loadingwithin the piping or another portion of a pressurized system. Suchirregular loading can deform a seal provided within the valve body,thereby negatively affecting the seal's performance. To replace a knownseal provided in the valve body, the valve must be disassembled, whichmay be costly and time-consuming. Additionally, a known valve positionsthe seal perpendicular to the flow when the valve is open, which mayincrease the risk that the seal could be damaged and/or torn out asfluid passes through the valve.

There is a need for a pressure relief device that overcomes one or moreof the deficiencies above and/or other deficiencies in the art, and/orprovides additional benefits.

SUMMARY

According to one embodiment, a rotatable pressure relief valve assemblycomprises a body defining an inner surface and a plug mounted within thebody. The plug is rotatable between an open position and a closedposition. A seal is provided with the plug and is configured to form afluid-tight barrier with the body when the plug is in the closedposition.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments and togetherwith the description, serve to explain the principles of the disclosure.

FIG. 1 illustrates a cross-sectional view of a rotatable valve assembly.

FIG. 2 illustrates a view of the inlet side of the rotatable valveassembly illustrated in FIG. 1.

FIGS. 3-5 illustrate the rotatable valve assembly of FIG. 1 inoperation.

FIG. 6 illustrates another embodiment of a rotatable valve assembly.

FIG. 7 illustrates yet another embodiment of a rotatable valve assembly.

FIG. 8 is a detail view of the rotatable valve assembly of FIG. 7,illustrating a clamp and a seal.

FIG. 9 is a perspective view of still another embodiment of a rotatablevalve assembly.

FIG. 10 is a cross-sectional view of the rotatable valve assembly ofFIG. 9.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present exemplaryembodiments, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. The drawingfigures of this application are intended to provide a generalunderstanding of the working elements of the underlying system.Accordingly, unless explicitly stated, the figures do not represent aliteral depiction of proportional dimensions or the precise locationsfor the illustrated inter-related components.

FIG. 1 illustrates one embodiment of a rotatable valve assembly 20 ofthe present disclosure, The assembly 20 includes a valve body 22, avalve plug 24, and a mount 26 for rotatably mounting the valve plug 24in the valve body 22 about a shaft 38 defining a rotational axis 28. Thebody 22 has an inlet 46 and an outlet 48 defining a fluid passageway 50through the body 22. The inlet 46 of the body 22 receives fluid andpressure from a fluid pressure source (not illustrated), such as avessel or piping.

The shaft 38 may extend through the body 22 and may be rotatable withthe plug 24, relative to the body 22, about the rotational axis 28. Theshaft 38 may be a single, continuous shaft extending across a face of orthrough the plug 24, or may be one or more shaft ends, axles, ears, orthe like which extend from the plug 24 through the body 22. Limitswitches, motion detection switches, or the like (not shown) may beprovided at either or both outside ends of the shaft 38 to indicatewhether the plug 24 is in the open or closed position and/or has beenopened or closed.

The valve assembly 20 may further include a seal 96 for sealing the gapbetween the circumferential perimeter of the valve plug 24 and the fluidpassageway 50 of the valve body 22, when the valve plug 24 is in theclosed position. Unlike a known rotatable valve (in which a seal isprovided within the valve body), the seal 96 of the illustratedembodiment is provided within the valve plug 24.

Providing the seal 96 within the plug 24 provides advantages over aknown valve (which includes the seal within the valve body).Specifically, providing a seal 96 within the plug 24 provides moreprecise control of the sealing mechanism, including the interfacebetween the moving (e.g., plug 24) and non-moving (e.g., body 22) partsof the valve assembly. In addition, a seal provided within a plug 24 iskept apart from the forces communicated to the valve body 22 when thevalve body 22 is installed within piping or another portion of apressurized system. It has been observed that irregular loading ofpiping—particularly on larger nominal size piping systems—can lead toproblems, including the development of deformation within the valvebody. Such deformation may impair the performance of a body-mountedseal. According to the present disclosure, however, the seal 96 isindependent from the deformation of the valve body 22.

Providing a seal 96 within a plug 24 may also provide an advantage whenreplacing the seal 96. Rather than disassemble the entire valve and/orremove the valve body from the piping or other pressurized system (as isrequired to replace known in-body seals), the seal may be replaced withthe valve intact and/or installed. Additionally, or alternatively, thevalve plug 24 may be removed for seal 96 replacement, while the body 22is left intact.

Providing a seal 96 within a plug 24 may also provide an advantage whenthe valve is opened. When the disclosed plug 24 and seal 96 open, suchthat fluid may escape the valve, the seal 96 may be positioned otherthan perpendicularly to the fluid flow path. In one embodiment, the seal96 may be positioned substantially parallel to the fluid flow path whenthe valve is opened. When a known seal is positioned perpendicular to afluid flow path, the fluid may be more likely to damage or tear out theseal. Thus, by positioning the seal 96 on the plug 24 as disclosed, theseal 96 may be protected from such damage.

As illustrated in FIG. 1, the valve body 22 is provided with a matingsurface 98 configured to mate with the seal 96. The properties of matingsurface 98 (e.g., material or shape) may be selected to optimize theinterface with the seal 96. For example, the attributes of matingsurface 98 may be selected to reduce or increase friction between matingsurface 98 and the seal 96. The mating surface 98 may be made of thesame material as the valve body 22, or the mating surface 98 may be madeof a different material. The mating surface 98 may be formed integrallywithin the valve body 22, or the mating surface 98 may be an addedcomponent or added layer inserted into and/or mounted on valve body 22.The mating surface 98 also may be shaped to achieve a desired interfacewith the seal 96.

As illustrated in FIG. 1, the valve plug 24 may be mounted for eccentricrotation in the passageway 50. The rotational axis 28 of the shaft 38and plug 24 is offset in at least one direction from the diameter of theplug 24. As a result, the first portion 124 of the plug 24 on the firstside of the rotational axis 28 is larger and has greater area exposed tothe inlet fluid pressure than the second portion 128 of the plug 24 onthe second side of the rotational axis 28. This creates a moment andtorque about the rotational axis 28 and shaft 38. This arrangement hasanother advantage in that the shaft 38 partially balances the fluidpressure on either side of the rotational axis 28 and shaft 38 andtherefore reduces the force which the plug 24 must directly resist toseal. As shown in FIG. 1, the rotational axis 28 of the shaft is offsetfrom the central axis of the passageway 50. It also is contemplated thatthe rotational axis 28 of the shaft may additionally or alternatively beoffset upstream or downstream from the plug seal (for example asillustrated in FIG. 6, discussed below).

When valve plug 24 is in a closed position, a pressure in thepressurized system generates a torque on the valve plug 24 aboutrotational axis 28. As illustrated in FIG. 2, the assembly may include arelease mechanism 40 configured to prevent the valve plug 24 fromrotating from the closed position when the torque about rotational axis28 is below a selected magnitude and for releasing the plug 24 and shaft38 to rotate to an open position when the torque exerted around therotational axis 28 exceeds a selected magnitude. Additionally oralternatively, the valve plug and/or release mechanism may be preloaded(e.g., with a spring), such as is disclosed, e.g., in co-owned U.S. Pat.No. 6,491,055, the entire contents of which are expressly incorporatedabove. Preloading may assist to engage the plug seal into a sealedposition.

In one embodiment, the release mechanism 40 includes a failure pin 54.As illustrated, the failure pin 54 is mounted on the valve body 22. Therelease mechanism 40 also includes a contact arm 66, which translatesthe torque around the rotational axis 28 into a load applied to thefailure pin 54. The failure pin 54 is configured to deform and/or failunder a predetermined load applied by the contact arm 66. The failurepin 54 may be a permanently or irreversibly deformable structure, whichbends or breaks when subjected to a predetermined load. Although afailure pin 54 is illustrated, the disclosure contemplates the use ofany suitable mechanism configured to deform and/or fail under apredetermined load, including but not limited to, a beam, bar, plate,disk, spring, or comparable structure (or any combination thereof). Suchmechanisms may be permanently or irreversibly deformable. Alternatively,such mechanisms may be reversibly deformable, such that they return toan initial condition once a deforming load is removed. As noted above, arelease mechanism may be preloaded. For example, a failure pin 54 orother deformable failure mechanism may be subject to preloading toreduce the fluid pressure necessary to generate the output forcenecessary to deform the failure mechanism and open the valve. Co-ownedU.S. Pat. No. 6,491,055, expressly incorporated above in its entirety,discloses an exemplary preloading mechanism.

As illustrated in FIG. 2, the failure pin 54 is subjected to abending-type load applied by the contact arm 66. It is also contemplatedthat the failure pin 54 (or other suitable failure mechanism) may besubject to a different type of loading, such as compression, tension, orshear, as illustrated in FIGS. 4-6 of U.S. Pat. No. 5,947,445 (theentire contents of which is incorporated herein by reference). It isfurther contemplated that a release mechanism may include a magneticcatch configured to prevent the valve plug from rotating until apredetermined load overcomes a magnetic attractive force, as illustratedin FIG. 7 of U.S. Pat. No. 5,947,445 (the entire contents of which isincorporated herein by reference). In another embodiment, the disclosedvalve assembly may be used with a linkage assembly such as disclosed inU.S. Pat. Nos. 6,367,498, 6,448,044, and 6,491,055 (the entire contentsof which are incorporated herein by reference) to control the opening ofthe valve plug.

FIGS. 3-5 illustrate the valve assembly of FIG. 1 in operation, Asillustrated in FIG. 3, the valve plug 24 is in a closed position, andthe seal 96 forms a fluid-tight seal against the mating surface 98 ofthe valve body 22. In FIG. 4, the fluid-tight seal has begun to break asthe valve plug 24 moves away from the closed position. In FIG. 5, thevalve plug 24 is in a fully opened position, allowing fluid to escapethe pressurized system.

FIG. 6 illustrates another embodiment of a rotatable valve assembly 220according to the present disclosure. As illustrated, the assembly 220includes a valve plug 224 mounted within a valve body 222 through a pairof rotatable shafts 238. A seal 296 is retained within the valve plug224 by way of a clamp 260. The valve body 222 includes a mating surface298 configured to mate with the valve seal 296 in the valve plug 224when the valve plug 224 is in a closed position. As illustrated, theinner surface of the valve body 222 may be curved to accommodate therotation of valve plug 224. Also as illustrated, the axis of rotation ofrotatable shafts 238 is offset downstream from the seal 296.

FIGS. 7-8 illustrate another embodiment of a rotatable valve assembly320. As illustrated, the assembly 320 includes a valve plug 324 mountedwithin a valve body 322 through a pair of rotatable shafts 338. A seal396 is retained within the valve plug 324 by way of a clamp 360. Asillustrated, the clamp 360 is clamped to the plug 324 using one or morescrews 361 (FIG. 8). Additionally or alternatively, any other suitableclamping mechanism may be used to clamp the seal 396 into the plug 324.The seal 396 is clamped in a manner that places the sealing portion ofthe seal 396 in the desired location to achieve a leak-tight interfacewith a mating surface 398 of the valve body 322 when the plug 324 is inthe closed position. As illustrated, the inner surface of the valve body322 may be curved to accommodate the rotation of valve plug 324.

FIG. 8 shows a detailed view of the rotatable valve assembly 320illustrated in FIG. 7. The seal 396 illustrated in FIG. 8 is a“double-lip” seal, which may be useful to achieve leak tightness in bothflow directions (i.e., into and out of the pressurized system). However,the disclosure is not limited to any particular type of sealconfiguration. For example, it is contemplated that an ‘O’-ring seal,wiper-type seal, or peninsula-type seal (which may project outwardlyfrom a sealing surface) may be used. The seal may be configured suchthat increased inlet pressure may increase the sealing quality betweenthe valve plug and valve body. For example, pressure on the inlet sideof the double-lip seal 396 illustrated in FIG. 8 may cause theinlet-side lip to seal more strongly with the mating surface 398 (atleast until the valve's opening pressure is reached and the plug isallowed to rotate). In one embodiment, a seal may be generated from acoating material applied to the valve plug. Additionally, although theseal illustrated in FIG. 8 is shown as a separate component clamped intothe valve plug 324, it is also contemplated that a seal may beintegrally formed within the valve plug.

FIG. 8 illustrates that the interface between the seal 396 and matingsurface 398 may be offset from and form an angle with respect to thecentral axis of the fluid passageway (not shown in FIG. 8). In thismanner, the seal 396 and mating surface 398 may contact one another onlywhen the valve is in a closed position, such that friction between theseal 396 and mating surface 398 may be minimized or eliminated while theplug 324 is rotating toward an open position. It is contemplated thatthe features of an offset seal angle (as illustrated in FIG. 8) may becombined with the features of an offset rotational axis (FIG. 1 and FIG.6) to achieve a double- or triple-offset configuration.

Another embodiment of a rotatable valve assembly 420 is illustrated inFIGS. 9 and 10. As shown, the valve assembly 420 includes a valve body422. Body 422 has a flange 471 that contains a series of bolt holes 472.In one embodiment, bolt holes 472 are positioned in flange 471 toconform to the standard ANSI bolt pattern (or other standardized boltpattern) for a pipe flange with a similar nominal size. Bolts, or otherconnecting devices, may be used to engage flange 471 with acorresponding pipe flange that is connected to a pressurized system (notshown). However, it is also contemplated that the rotatable valveassembly of the present disclosure may be engaged with the pressurizedsystem in any other manner readily apparent to one skilled in the art.

As illustrated in FIG. 10, body 422 includes an inner surface thatdefines a fluid flowpath 450 having an inlet 446 and an outlet 448.Inner surface of body 422 may have a spherical or curved shape. Whenflange 471 (FIG. 9) is engaged with a pipe flange of a pressurizedsystem, the system pipe flange guides pressurized fluid in the directionindicated by arrow P and into body 422, which directs the pressurizedfluid into inlet 446.

A disclosed valve may include a shaft rotatably mounted in the body anda plug disposed in the fluid flowpath. The plug may be mounted on theshaft and may be rotatable between a closed position, where the plugprevents pressurized fluid from flowing through the fluid flowpath, andan open position, where pressurized fluid may be allowed to flow throughthe fluid flowpath. In one embodiment, the plug may be mounted on theshaft in an offset manner such that when the plug is in the closedposition, the pressurized fluid acts on the plug to exert a torque onthe shaft to rotate the plug from the closed position to the openposition.

As illustrated in FIG. 10, a shaft 438 is rotatably mounted in body 422.Shaft 438 includes an exterior end that extends through body 422 and aninterior end that extends into the plug 424. A bearing, such as rollerbearing or a bushing, may be positioned between shaft 438 and body 422to facilitate rotation of the shaft within body.

As is also shown in FIG. 10, a plug 424 is disposed within fluidflowpath 450. In one embodiment, plug 424 may include opposing sideswith an internal passageway therebetween. As illustrated in FIG. 10, theplug 424 includes an inlet plate 468 and an outlet plate 469 that arejoined together. In one embodiment, the inlet and outlet plates have acurved cross-sectional shape that generally conforms to the contour ofinner surface of body 422. It is contemplated, however, that the innersurface of the valve body may form a straight bore on one or more sides,and the valve plug may be shaped accordingly. In addition, the plug mayhave alternative configurations, including a single plate design or amultiple plate design.

Referring again to FIG. 10, a second shaft 439 is rotatably mounted inbody 422 opposite shaft 438. As with shaft 438, shaft 439 includes aninterior end extending into fluid flowpath 450 (and into plug 424) and abearing, such as roller bearing or a bushing, may be positioned betweenshaft 439 and body 422 to facilitate rotation of shaft 439 within body422. Because shafts 438 and 439 are rotatably mounted in body 422, plug424 is similarly rotatable with respect to body 422. Plug 424 may berotated between a closed position, where the plug is substantiallyperpendicular to the direction of fluid flow, and an open position,where the plug is substantially parallel to the direction of fluid flow.

A seal 496 is disposed in the plug 424 of FIG. 10, As shown, the seal496 is disposed in the inlet plate 468 of the valve plug 424. A seal maybe provided additionally or alternatively in the outlet plate 469 of thevalve plug 424. The seal 496 may be configured to provide a line sealengageable with a portion of the inner surface of the body 422 toprevent pressurized fluid from flowing between the plug and the body.Seal 496 may extend around the circumference of plug 424. In oneembodiment, the seal 496 may be made of a soft, elastic material, suchas a fluoroelastomer.

In one embodiment, the seal 496 may engage the body for between about1.5 degrees and 5 degrees of rotation of the plug 424 between the closedposition and the open position. The use of a line seal with a globed orspherical surface may result in a low torque valve that is more readilyopened and reclosed. As such, the valve may be useful in low-pressureapplications. Using a hollow plug 424 may reduce the mass that is movedbetween the open and closed positions, which also makes the valve usefulfor low-pressure applications.

As illustrated in FIG. 10, a replaceable seat 498 may be disposed on theinner surface of valve body 422. Seat 498 may be constructed of metal.Seat 498 may be constructed of the same material as valve body 422. Inanother embodiment, seat 498 may be constructed of a soft material, ormay be constructed of the same material as seal 496. It is contemplatedthat the outer surface of replaceable seat 498 may include a coating,such as polytetrafluoroethylene (PTFE), to reduce the friction betweenthe seal and the plug and allow the plug to more freely open in lowpressure applications. Other coatings and materials may be selected tochange other attributes of the interface between the seal and the plug.

A retaining ring (not shown) may engage with the valve plug 424 to holdseal 496 in place. In one embodiment, the valve plug 424 and theretaining ring may be configured so that the retaining ring may beengaged with valve plug 424 with a press-fit. The present inventioncontemplates that the retaining ring may be engaged with the valve plugby other methods, such as, for example, corresponding threads on theretaining ring and valve plug.

It is contemplated that the described rotatable pressure relief valvemay be used as a reclosing valve or a non-reclosing valve. In oneembodiment of a non-reclosing valve, the plug 424 may rotate throughapproximately 90 degrees in moving from the closed position to the openposition. This places the inlet and outlet plates 468, 469 substantiallyparallel to the direction of fluid flow to afford the highest fluid flowrate to most efficiently reduce the pressure within the system. In anembodiment of a reclosing valve, the plug 424 may rotate through lessthan 90 degrees (e.g., approximately 85 degrees) in moving from theclosed position to the fully open position, In this position, the inletand outlet plates 468, 469 are positioned such that the fluid continuesto exert a force on the plug. When the pressure of the fluid, and theresultant force on the plug, drop below a certain limit, a spring orother similar mechanism (not shown) may rotate the plug back to theclosed position.

A position indicator (not shown) may be used to indicate whether theplug is in the open position or in the closed position, In oneembodiment, a position indicator may be attached to shaft 439 and may beviewed through a transparent cap on the valve body 422.

In addition to a seal on the valve plug, it is further contemplated thata second seal may also be mounted on the valve body. In such anembodiment, the body seal and the plug seal may seal against one anotherto create a fluid-tight interface. Using cooperative seals may bedesirable to alter the effects of friction between the sealing surfaces.For example, to ease the closing and opening of the valve, the materialsor shapes of the cooperative seals may be selected to reduce frictionbetween them. Alternatively, it may be desirable to choose sealmaterials and shapes to increase friction between the seals and/orbetween the seal and valve body. Furthermore, the cooperative seals maybe shaped to interlock with one another to strengthen or otherwiseachieve a desired sealed interface.

The foregoing embodiments are exemplary only. Other embodiments will beapparent to those skilled in the art from consideration of thespecification and practice of the disclosure herein.

What is claimed is:
 1. A rotatable pressure relief valve assembly,comprising: a body defining an inner surface, the plug having a centralaxis defining a fluid flow path; a plug mounted within the body, theplug being rotatable between an open position and a closed position; aseal attached to the plug and configured to form a fluid-tight barrierwith the inner surface of the body when the plug is in the closedposition; and, a shaft coupled with the plug to allow the plug to rotatebetween an open position and a closed position; wherein the innersurface of the body is curved along a cross-section along the centralaxis, wherein the curve is configured to accommodate the rotation of theplug; and, wherein the shaft defines a rotational axis; the body definesa fluid passageway having a central axis, and the wherein the rotationalaxis of the shaft is offset from the central axis of the fluidpassageway.
 2. The valve assembly of claim 1, wherein the seal is adouble-lip seal having an inlet-side lip and an outlet-side lip, whereinthe inlet-side lip is configured to be exposed to a pressure on an inletside of the plug, and wherein the inlet-side lip is further configuredto increase a sealing pressure against the inner surface of the body inresponse to an increase in the pressure on the inlet side of the plug.3. The valve assembly of claim 1, wherein the seal is formed from acoating applied to the plug.
 4. The valve assembly of claim 1, furthercomprising: a clamp, wherein the clamp is configured to retain the sealagainst the plug.
 5. The valve assembly of claim 1, wherein the seal isa first seal, further comprising: a second seal provided in the body;and wherein the first seal and second seal are configured to form thefluid-tight barrier when the plug is in the closed position.
 6. Thevalve assembly of claim 5, wherein the first seal is formed from a firstmaterial, wherein the second seal is formed from a second material, andwherein the first material and second material are the same material. 7.A rotatable pressure relief valve assembly, comprising: a body definingan inner surface, the plug having a central axis defining a fluid flowpath; a plug mounted within the body, the plug being rotatable betweenan open position and a closed position; a seal attached to the plug andconfigured to form a fluid-tight barrier with the inner surface of thebody when the plug is in the closed position; and, a release mechanismconfigured to keep the plug in the closed position until a predeterminedfluid pressure differential is applied to the plug; wherein the innersurface of the body is curved along a cross-section along the centralaxis, wherein the curve is configured to accommodate the rotation of theplug.
 8. The valve assembly of claim 7, wherein the release mechanismcomprises at least one of a failure pin, a beam, a bar, a plate, a disk,or a spring configured to deform when the predetermined fluid pressuredifferential is applied to the plug.
 9. The valve assembly of claim 1,wherein the valve body comprises a replaceable seat disposed on theinner surface of the valve body.
 10. The valve assembly of claim 1,wherein the valve plug is a reclosing valve plug.